This section is from the book "Practical Dietetics With Special Reference To Diet In Disease", by William Gilman Thompson. Also available from Amazon: Practical Dietetics with Special Reference to Diet in Disease.
Indigestion and dyspepsia are terms which refer essentially to functional slight and often temporary derangement of the digestive system, although these conditions may result from many varieties of disease, especially from fever due to almost any cause. The terms are used somewhat vaguely to include a number of minor symptoms, such as weight and oppression at the epigastrium and praecordium, eructations, "water brash," palpitations, vertigo, headache, modified taste and thirst sensations, loss of appetite or morbid craving for certain indigestible articles of food, flatulency, hiccough, and sometimes nausea, heartburn, pain referred to the cardiac end of the stomach, lassitude, irritability, drowsiness or restlessness, and despondency. As Sir Henry Thompson said: "The word indigestion denotes not a disease, but an admonition".
Fothergill wrote: "If it were not for the protection of indigestion, of which many so bitterly and ungratefully complain, the lives of a large number of individuals would not attain their furthest potential expansion".
Many of these symptoms, especially those referable to the nervous and vascular systems, are explained by the belief that morbid products which closely resemble poisonous alkaloids in their action (as indeed in their composition), and which are called ptomaines or leucomaines, are easily absorbed, and produce effects varying in intensity from slight headache to the collapse of violent ptomaine poisoning (p. 379). Other symptoms are doubtless due to imperfect elimination of waste matter of food or "ashes " from the system.
Bauer says:" It is beyond doubt that insufficient secretion is the essential cause of most dyspeptic symptoms as they appear in various disorders of the stomach".
As a rule, the acid gives out before the pepsin, and a deficiency of acid is a very common condition, especially in anaemia. Anaemia produced experimentally by repeated bleeding of animals will cause it.
Chronic hyperaemia and inflammation of the stomach excited by coarse irritating food have the same result, and the free acid, if secreted, is neutralised by abundant mucus.
Deficiency of hydrochloric acid in the gastric juice has a threefold effect: I, Failure to digest proteids; 2, failure to arrest mal-fermentation or putrefactive changes in the food; 3, failure to excite gastric peristalsis, so that the food lingers too long in the stomach. Other causes of delay may be found in too large a bulk of food, lack of peristalsis, and obstruction through stenosis of the pylorus without corresponding increase in contractile power of the stomach.
The normal gases of the stomach are those of atmospheric air; but food which is improperly fermenting is capable of evolving others, and those which have been determined by analysis of eructations are C02,H2,02N2,CH4 (marsh gas) C2H4 (olefiant gas). Ewald reports a case in which sufficient marsh gas was evolved from the stomach to burn with a pale-yellow flame.
Some degree of lactic-acid fermentation may be a normal accompaniment of gastric digestion, but the process is easily carried too far; butyric acid develops, and gases are evolved. This action resembles that produced outside the body when decomposing albumin comes in contact with saccharine substances.
Distention of the stomach and intestine with gas interferes with the free play of the diaphragm in the respiratory movements, and since the heart lies upon its side, separated from the stomach only by the diaphragm, an inflated stomach compresses and displaces the heart, interfering with its rhythm and force and causing palpitations. The latter, in connection with impeded extent of movement of the diaphragm, produces dyspnoea, especially on exertion.
Pain is a very frequent accompaniment of dyspepsia. It is usually of a dull aching variety, but is sometimes sharp and acute. It is often erroneously referred to the heart, but it is due rather to hyperaesthesia of the stomach wall, excited by products of imperfect digestion.
In all diseases of the stomach the retention of any particles of undigested food gives rise to irritation and malfermentation, which still further complicates the diseased condition of the organ itself and interferes with its proper action upon fresh quantities of food. This may be occasionally relieved by vomiting or by the ingestion of some simple fluid which will aid in washing the stomach contents onward into the intestine.